Add conflics

OBS-URL: https://build.opensuse.org/package/show/Archiving/zstd?expand=0&rev=76

zstd.spec

@@ -89,6 +89,8 @@ Needed for compiling programs that link with the library.
 Summary:        zstd and zlib based gzip drop-in
 Group:          Productivity/Archiving/Compression
 Conflicts:      alternative(gzip)
+Conflicts:      gzip
+Conflicts:      busybox-gzip
 Provides:       gzip
 Provides:       alternative(gzip)
 Requires:       %{name} >= %{version}